Air gun



FIG. 1 is a perspective view of an air gun, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right-side elevation view thereof;

FIG. 5 is a left-side elevation view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a top plan view thereof. 

CLAIM The ornamental design for an air gun, as shown and described. 